blending error

[xiuliren]

the same image works fine locally, but have error in AWS cloud while large scale inference.

https://files.slack.com/files-pri/T02FH1DRA-F5RR27HAB/pasted_image_at_2017_06_08_04_49_pm.png

[xiuliren]

@torms3 @supersergiy
It looks that the blending error may come from async blending. the current_idx could be messed up among threads here?
https://github.com/torms3/DataProvider/blob/async_blend/python/forward.py#L82 (edited)

[2:26]
https://github.com/torms3/DataProvider/blob/async_blend/python/forward.py#L72